[Crash-utility] [PATCH] add log -T option to display the message text with human readable timestamp

[Dave Anderson]

----- Original Message -----
> 
> 
> On 20/4/2020 3:48 am, Dave Anderson wrote:
> > 
> > FWIW, I tried it on another RHEL7 machine running live,
> > but then also on a RHEL8 kernel dumpfile, and they all hang:
> 
> I apply this patch on RHEL7 virtual machine(VirtualBbox) and it work ok.
> and on a RHEL7 kernel dumpfile, I found it hang after I send the patch.
> 
> 
> and I debug it and found the  machdep->hz == 0 on the following:
> 
>            get_uptime(NULL, &uptime_jiffies);
>            uptime_sec = (uptime_jiffies)/(ulonglong)machdep->hz;
>            kt->boot_date.tv_sec = kt->date.tv_sec - uptime_sec;
>            kt->boot_date.tv_nsec = 0;
> 
> because machdep-> hz has not been initialized here.  divide by zero make
> the cpu spinning at 100%.
> 
> I thought two solutions:
> 
> (1) add misc_init function after machdep_init(POST_INIT) call, and
> calculate the value of kt-> boot_date in it.
>                          read_in_kernel_config(IKCFG_INIT);
>                          kernel_init();
>                          machdep_init(POST_GDB);
>                          vm_init();
>                          machdep_init(POST_VM);
>                          module_init();
>                          help_init();
>                          task_init();
>                          vfs_init();
>                          net_init();
>                          dev_init();
>                          machdep_init(POST_INIT);
> +                       misc_init();
> 
> (2) calculate the value of kt-> boot_date on cmd_log function, when we
> call log command.
> 
> 
> Dave, Which one do you like?

Definitely option #2.  Since it's not required unless your new command option is run,
you can simply check whether the new boot_date structure is still zero-filled, and do
your initialization at that time.

And BTW, please move the boot_date structure to the end of the kernel_table
to prevent any possible breakage of previously-compiled extension modules
that use the kernel_table.  And also can you please display the new structure's
contents in dump_kernel_table()?  You can put the display under the current
"date" display.

Thanks,
  Dave